Researchers are working to find the best approaches to treating triple-negative breast cancer. Some clinical trials are comparing the effectiveness of various older and newer chemotherapy medications, used in different combinations, for treating triple-negative breast cancer.
Other clinical trials are trying to find out whether some targeted therapies are effective against triple-negative breast cancer. Unlike traditional therapies such as chemotherapy and radiation, which can’t tell the difference between fast-growing healthy cells and cancer cells, targeted therapies work by “shutting down” a specific process the cancer cells use to grow and thrive. We know that targeting estrogen and progesterone receptors and HER2 isn’t helpful for triple-negative breast cancer. Treatments that target other processes may be helpful in the future, but this research is still at an early stage.
- PARP (poly ADP-ribose polymerase) inhibitors: The PARP (poly ADP-ribose polymerase) enzyme fixes DNA damage in cells, including DNA damage caused by chemotherapy medicines. Scientists developed PARP inhibitors based on the idea that a medicine that interferes with or inhibits the PARP enzyme might make it harder for cancer cells to fix damaged DNA, which could make chemotherapy more effective. In 2018, the U.S. Food and Drug Administration approved Lynparza (chemical name: olaparib) as the first PARP inhibitor to treat breast cancer. Lynparza is used to treat metastatic, HER2-negative breast cancer in women with a BRCA1 or BRCA2 mutation that has been previously treated with chemotherapy.
- VEGF (vascular endothelial growth factor) inhibitors: To get the oxygen and nutrients they need to grow and spread, tumors create new blood vessels through a process called angiogenesis. Avastin (chemical name: bevacizumab) is a medicine that interferes with the activity of the VEGF protein, which stimulates this process. Avastin attaches itself to VEGF, preventing VEGF from interacting with receptors on the blood vessels. By blocking this interaction, Avastin keeps VEGF from stimulating angiogenesis. Another therapy that works in a similar way is Sutent (chemical name: sutinib).
- EGFR (epidermal growth factor receptor)-targeted therapies: Other treatments target a protein called epidermal growth factor receptor, or EGFR. Many triple-negative breast cancer cells are known to “overexpress” EGFR, meaning they have too many EGFRs. These receptors receive signals that spur the growth of the cancer. Erbitux (chemical name: cetuximab) is a medication that attaches to the EGFR. When this happens, growth signals can’t attach to EGFR on the cancer cell, and so they cannot stimulate the cell to grow.
Clinical trials using these and other therapies could play a key role in improving the treatment of triple-negative breast cancer. Talk to your doctor if you think you might be interested in taking part in a clinical trial.